Method of hot plating containers



Patented Jan. is, 1938 METHOD OF nor PLATING CONTAINERS Isaie J/B. Demers, St. Paul, Minn., assignor to Superior Metal Products Company, St. Paul, Minn., a corporation of Delaware Application October 26, 1936, Serial No. 107,601

'1 Claims.

It is an object of this invention to provide a novel process for hot plating the walls and bottoms of containers simultaneously and in such manner that thethickest plating is located on the bottoms and adjacent parts which are subjected to the most harmful wear and corroding influences.

A further object is to provide a novel process for obtaining improved distribution of the plating material on a container having a closed bottom and at the same time to eliminate waste of plating material by avoiding unnecessary thickness of plating and accidental spilling of the plating.

. Other objects will appear and be more fully pointed out in the following specification and claims.

In the manufacture of many types of sheet metal containers, such for example as those used for dairy products, it is desirable, in the interest of economy and to avoid unsightly and unsanitary joints, to weld the bottoms tr: the walls before the plating operation. When this is done, however, the problem of obtaining. the proper distribution of the plating material to impart maximum durability to the container is rendered more difiicult, particularly where the finished containers have no bottom opening which can.

be utilizedas an outlet for the excess of plating material during the plating process. One method of solving this problem is described and claimed in my Patent No. 2,018,951, dated October 29, 1935. By the method described and claimed herein I eliminate the necessity for an opening or perforation in the bottom of the container and at the same time secure the advantages of increased thickness of plating material on the bottom and lower portions of the walls of the containers. I

My improved method and suitable apparatus for practicing it is illustrated in the accompanying drawing in which,

Figure 1 is a central, vertical section through a container and listing table supporting the con- 45 talner and also illustrating a. device for removing the excess of plating material;

Fig. 2' is a larger vertical section through the bottom portions of the container and removing device, and

removing device.

In the drawing, a milk can is indicated generally by the numeral 4. The principal parts of this can are assembled in the usual or suitable 65 manner, preferably by welding the top portions Fig. 3 illustrates the method of emptying the and bottom 5 to the cylindrical walls 6. The bottom 5 is internally concave in shape and a small indentation I is preferably formed centrally therein to facilitate removal of the excess plating material, as hereinafter described.

As a preliminary to the plating or tinning of the containers, the latter are thoroughly cleansed, usually in an acid bath. The entire container is now immersed in a bath of the molten plating metal so that the latter completely covers the inner and outer surfaces of the container. Two or more immersions in the plating material are usually required. After the final immersion in the plating material, the greater part of the excess from the interior surfaces is decanted from the top and then the container is supported in upright position, as indicated in Figs. 1 and 2 of the drawing while the plating cools and hardens.

During this step of the process containers are usually placed on a listing plate 8, shown diagrammatically in Fig. 1. This plate is supported in horizontal position in the top of a kettle or vat 9 containing a body of the plating material which is maintained in its molten condition by heating. Suitable burners are well known in this art andare shown diagrammatically in the drawing, being indicated by the numeral Iii. The surface of the metal is maintained slightly above the plate 8 so that the lower extremity of the container 4 rests in the hot metal while the excess of plating material from the exterior of the container flows into' the vat 9.

While thus positioned on the listing plate, the

container cools progressively from the top down and ithe excess of plating material from the interior surfaces collects in a small pool, indicated by the numeral H in Fig. 2, on the bottom in and aroundv the'depression 1. While this pool is still molten, ,it is removed directly upward so as not to spread or spill the metalon the solidified coating elsewhere on the container. Finally, when the container is sufiiciently cool for removal from the listing plate, the entire surfaces are smoothly plated without excess or irregular deposits and the desired maximum thickness of plating on the bottom and adjacent parts is obtained.

To facilitate the removal of the pool ll of molten metal, I provide a small receptacle l2 mounted on a pipe l3 and formed with a passage l4 terminating in a short nipple l5 at its lower end. This passage communicates with the interiorof the receptacle l2 at a point spaced upward from the bottom of said receptacle. By

this arrangement," a quantity of molten metal i may be trapped in the receptacle l2 for removal from the container 4. The pipe l3 communicates at its upper end with a hose I! connected to a vacuum tank or other device for exhausting air from the receptacle II. The application of the reduced pressure may be controlled by a valve it. The passage I l is preferably located at one side of the receptacle [2 to facilitate the discharge of the metal I 6 from the receptacle. As illustrated in Fig. 3, the device when not in use is preferably placed on its side so that the metal it flows out through the passage 44 and should be kept hot between operations by supporting it above or in a flame. A burner IQ for heating the receptacle I2 is indicated in Fig. 3. The pool of coating material ll may be quickly removed, at the proper time as hereinbefore described, merely by lowering the receptacle I2 into the container and submerging the tip of the nipple E5 in the pool, while the vacuum is applied through the pipe l3 and hose IT. The receptacle i2 is then withdrawn from the container and emptied. By my arrangement of the passage ill, the molten plating material is trapped in the receptacle l2 and there is no dripping or other defacing of the hardened plating as the device is withdrawn from the container. Between operations, the receptacle I2 is placed on its side, as indicated in Fig. 3, to empty the coating material through the passage I.

By reason of the cooling in upright position and fact that the lower portions of the container 4 retain the heat longest, I secure smooth plating 20 on the walls 6 and bottom 5 which is progressively thicker from the top down. This is the condition desired because it affords the maximum protection when needed and an unusually durable container results.

My improved method may be employed in applying numerous plating materials, such as zinc or other galvanizing metals, as well as tin and other platings which are applied in a molten condition to various articles of manufacture, including tanks and cans of various types.

Having described my invention, what I claim as new and desire to protect by Letters Patent is 1. The method of hot plating a container having an imperforate' bottom which consists in applying a coating of molten plating material to said container, then placing it in such position as to accumulate a pool of excess coating material on said bottom while allowing said container to cool progressively from the top down and then removing said pool from above while in molten condition. 1

2. The method of hot plating a container to effect progressively increasing thickness of plating material toward the bottom which consists aroaeoe in securing to the walls of the container an imperforate bottom, then hot plating said container, then accumulating an excess of coating material on said bottom while allowing said container to partially cool and then removing said excess of plating material from above while in molten condition.

3. The method of hot plating a container having a bottom and walls which consists in applying acoating of molten plating material to said walls and bottom and then placing the container in such position as to accumulate the excess of coating material from the interior surfaces on said bottom while allowing said container to cool partially and then removing said excess of plating material by drawing it directly upward while in molten condition.

4. The method of hot plating a cylindrical container having an internally concave bottom which consists in immersing said container in hot plating material, then placing it in upright position and accumulating a quantity of the excess plating material on said bottom while allowing the container to cool progressively from the top down and then removing said excess of plating material from above while in molten condition and while retaining said container in substantially upright position.

5. The method of hot plating a container having an internally concave bottom which consists in immersing said container in hot plating material, then placing it in such position as to accumulate the excess of plating material from the interior surfaces of the container in apool on the inner surface of said bottom while allowing the container to partially cool and then removing said excess of plating material from above, while retaining said container in said position.

6. The method of hot plating a container which consists in forming in the inner surface of the bottom of said container an indentation, then hot plating said container and placing it in such position as to collect the excess of the liquid contents in and around said indentation and then allowing the container to cool progressively from the top down while withdrawing said excess of plating material from above and retaining said container in said position until the plating has hardened.

'7. The method of hot plating a container which consists in forming in the inner surface of the bottom of said container an indentation, then hot plating said container and placing it in such position as to collect the excess of the liquid contents in and around said indentation while allowing the container to partially cool, then withdrawing said excess of plating material from said indentation while retaining said container in said position.

ISAIE J. B. DEMERS. 

